Re: [PATCH RESEND] PCI/AER: Use a common function to print AER error bits

[Alex G.]

On 04/28/2018 11:46 AM, Alex G. wrote:
> On 04/27/2018 05:43 PM, Bjorn Helgaas wrote:
> > On Tue, Apr 17, 2018 at 12:09:43PM -0500, Alexandru Gagniuc wrote:
(snip)
> > > +ÂÂÂ memset(&info, 0, sizeof(info));
> > > +ÂÂÂ info.severity = aer_severity;
> > > +ÂÂÂ info.status = status;
> > > +ÂÂÂ info.mask = mask;
> > > +ÂÂÂ info.first_error = 0x1f;
> >
> > I like this patch a lot, but where does this "first_error = 0x1f" come
> > from?
>
> aer_(un)correctable_error_string don't go to [0x1f], so this guarantees 
> us we don't print "(First)".
>
> > I assume this is supposed to be the "First Error Pointer" in the
> > Advanced Error Capabilities and Control register (PCIe r4.0, sec
> > 7.8.4.7). There is a "cap_control" field in struct
> > aer_capability_regs; should we be using that here?
>
> There is a way to extract it from the PCI regs, and it's quite simple. 
> IIRC, it should be all f's when the capability is not implemented. I 
> wanted to avoid any further parsing of PCI regs in this patch.

I could update the offending line to say:
 +	info.first_error = PCI_ERR_CAP_FEP(aer->cap_control);

Though I still have the concerns with validating CPER data:

> I can see a way to use even more common printk code, but that requires 
> validating the PCI regs we get from firmware. That means we need to make 
> a guarantee about CPER that is beyond the scope of this patch.
>
> Alex